Electron tube switching apparatus



Oct. 4, 1955 M. w. SLATE ET AL ELECTRON TUBE SWITCHING APPARATUS Filed Dec. 50, 1952 Fig.3

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United States Patent ELECTRON TUBE SWITCHING APPARATUS Matthew W. Slate, New York, and Edward G. Mannerberg, Brooklyn, N. Y., assignors to Allen B. Du Mont Laboratories, Inc., Clifton, N. J., a corporation of Delaware Application December 30, 1952, Serial No. 328,589

Claims. (Cl. 250-27) This invention relates to electrical switching devices and particularly to electrical contactors in the so-called turret-type radio and television tuners.

Turret type tuners of the prior art employ a resilient contact arm which selectively engages different contact pins extending from a drum-type tuning turret. The contact arm must be comparatively long in length so as to achieve the required resiliency. This length has, inherently, relatively high values of inductance which is detrimental in tuners used at high frequencies.

An object of the present invention is to provide an electrical switching apparatus having a relatively short electrical connection to a resilient contact member.

Another object is to provide a resilient contact arm assembly having a reduced value of inductance.

Other objects will be apparent.

Referring to the drawing, Fig. 1 shows a front elevational view of a turret tuner in accordance with the invention.

Fig. 2 shows a modification of the apparatus of Fig. 1.

Fig. 3 is a side elevational view of the apparatus of Fig. 1, and

Fig. 4 is a front elevational view of a further modification of the invention.

As shown in Fig. 1, there is provided a turret 11 rotatable about an axis or shaft 12 and containing various tuned circuits which terminate in contact pins 13 arranged on the periphery of the turret 11. A resilient contact arm 16 is suitably affixed to a support member 17, and has a rounded or curved surface 18 at one end thereof positioned to make selective engagement with the various contact pins 13 when the turret 11 is rotated.

In the preferred embodiment of the invention, shown in Figs. 1 and 3, the contact arm arrangement has been modified and improved so as to reduce the inductance inherent in the prior art structures. The resilient contact arm 16 is affixed at one end 19 thereof to the support member 17. The remaining or curved end 18 makes electrical contact selectively with the various contact pins 13 on the turret 11. It is to be understood that the terminology curved used to describe the contact portion of the arm 26 is used in a general sense to include any suitable shape to make good sliding electrical contact.

A connector member 28, which preferably is somewhat resilient, is supported by any suitable support member 27 and an end thereof makes a wiping electrical contact with the curved end 18 of the arm 16. The connector pin 21 of the tube 22 is electrically connected to this wiping connector 28.

As may be seen, the length of electrical path between the various contact pins 13, through the connector 28, to the tube pin 21 is appreciably shorter than the length of the resilient arm 16. The wiping engagement of the connector 28 with the curved portion 18 of the arm 16 is sufficiently resilient so that the arm 16 may move in its normal manner when making and breaking electrical contact with the various connector pins 13. However, since the connector 28 does not move appreciably in performing its wiping contact function, it need not be as resilient nor as long as the arm 16. Although a tube 22 is shown as being connected to the connector 28, various other electrical circuits and devices may be connected thereto.

If desired, the connector 28 may comprise a tube pin 21, so that the curved contact 18 directly engages the tube pin, the curved portion 18 being sufliciently resilient to provide a good wiping contact. This modification is illustrated in Fig. 2.

In the embodiment of Fig. 4, the inductance is still further reduced. This embodiment is useful when a tube such as the tube type 6AF4, which has two plate lead pins and two grid lead pins, is employed. Two pins such as, for instance, plate lead pins designated by the numerals 31 and 32 are connected respectively to the end of the resilient arm 16 in the conventional manner, and to the connector member 28 in accordance with the present invention. This results in a combination electrical contact, with two parallel electric paths. The lead inductance between the turret connector pins 13 and the element in the tube 22 is thus reduced to a lower value than has heretofore been achieved in prior art systems.

If desired, a jumper" connection may be made between pins 31 and 32 at the tube 22.

The wiping contact, between the connector 28 and the resilient arm 16, is cleaned each time a contact pin 13 engages and raises the curved end 18, thereby providing a good electrical connection therebetween at all times. The connector 28, or alternatively the tube pin 21, preferably is positioned substantially perpendicular to the resilient arm 16 as shown, so that the connector 28 or pin 21 may be relatively short, thus providing reduced inductance between the turret 11 and the tube 22.

While preferred embodiments of the invention have been shown and described, various modifications thereof will be apparent to those skilled in the art. The scope of the invention is defined in the following claims.

What is claimed is:

1. Electrical switching apparatus comprising a resilient contact arm supported nearer one end thereof, a member movable with respect to said arm and having a contact pin thereon, means to selectively engage said contact pin with a portion of said arm, an electrical connector member positioned adjacent the other end of said arm and making electrical wiping contact therewith, and an electrical device connected to said connector member, the electric path between said portion of said arm and said electrical device having less inductance than that along the length of said resilient arm.

2. Electrical svw'tching apparatus comprising a resilient contact arm supported at one end and having the other end thereof curved to provide a contact surface, a member having a contact pin adapted to selectively engage said contact surface of said arm, a resilient electrical connector member positioned substantially perpendicular to said contact arm and making electrical wiping contact with said curved contact surface of said arm, and an electrical device connected to said connector memher, the electric path between said contact surface and said electrical device having less inductance than that along the length of said resilient arm.

3. The apparatus in accordance with claim 1, in which said electrical connector is a connector pin of an electronic tube.

4. The apparatus in accordance with claim 1, in which said electrical device is connected jointly to said contact arm and said connector member.

3 4v 5. The apparatus in accordance with claim 4, in which References Cited in the file of this patent said'electrical device is an electronic tube having a pair UNITED STATES PATENTS of connector pins connectedto an electrode within said tube, said connector pins being respectively connected 2142430 Wnkms 31 1939 to sa'd conne tor me b and to th su ort d endof 2431197 Flatt et a1 1947 said Contact m er 6 6 5 2,501,456 Thias et al. Mar. 21, 1950 

